This invention relates to an improved self-tailing winch for pulling a flexible line or rope and particularly adapted for use on sailing vessels.
For most winches heretofore used on boats, the rope or line to be pulled by the winch is wrapped around the winch drum and manually provided with tension as the winch is operated. On such winches it is necessary for the rope coming off of the drum to be paid out by hand or at least with hand assistance. To overcome these obvious disadvantages, attempts have been made to provide a so-called self tailing winch.
Self-tailing winches heretofore devised have utilized expensive V-groove pulley wheels fixed to a winch drum with the pulley wheel having transverse indentations corresponding to the shape of the rope in order to provide the necessary gripping power on the rope and prevent slippage. Such an arrangement is shown in U.S. Pat. No. 3,730,483. The present invention provides means for gripping the rope in a different manner and does not use a pulley or the specially shaped transverse indentations thereon, thereby eliminating unnecessary expense while providing increased effectiveness. The self-tailing winches with a pulley wheel heretofore in use also presented serious difficulties in operation due to the fact that different rope tensions and speeds occurred at the point where the rope was fed from the drum to the pulley wheel. This problem arose because for all but one particular diameter of rope, the rope in the pulley wheel could not get to the bottom of the V-groove and thus its loop diameter was greater than that on the winch drum. This created a differential speed between the rope on the pulley and the rope on the drum. Differential speeds between two such rope portions inevitably result in differential forces which cause trouble or made the winch difficult to operate. Often the tension created between the portion of rope on the pulley wheel and the portion on the drum was sufficient to break the rope. Thus, for a smooth operating self-tailing winch it is essential that the line speed of the rope unit entering the clamping means be identical to the line speed at which it leaves the winch drum so that no excessive tension forces exist. However, where a fixed pulley wheel is used, these speeds cannot be the same unless the diameter of the rope loop in the pulley groove is the same as the diameter of the rope loop on the drum from which it leaves.
Because of the aforesaid differential rope speed problem self-tailing winches having a pulley wheel with a fixed V-groove can be used with only one particular type of rope, or one diameter of rope in order to achieve the proper loop diameter, and this is a severe operating limitation. In the present invention it is possible to vary the rope diameter and the type of rope widely and still obtain satisfactory results, all without causing the differential speeds referred to above.
Therefore, among the objects of the invention are to provide a self-tailing winch which is both simpler in its general configuration and also more versatile in its operation.
Another object of the invention is to provide a self-tailing winch which will operate smoothly and efficiently with a wide variety of rope sizes and types, while still assuring proper pulling power and payout.
Another object of the invention is to provide a self-tailing winch with identical line speeds when entering the wheel and leaving the drum from which the rope is paid out, and to provide this even though the rope size may be varied.
Another more specific object of the invention is to provide a self-tailing winch which provides a winding drum with a line clamping and payout means on the drum and a line deflecting means mounted on top of the clamping means, all of which cooperate in an assembly comprised of a relatively small number of parts that are easy to assemble and maintain.
Still another object of the present invention is to provide an improved self-tailing winch that is particularly well adapted for ease and economy of manufacture.